US3149188A - Manufacture of ready-to-use cakes of soap and like cleansing materials - Google Patents

Description

v P 5, 1964 P. SCHMITT 3,149,188

MANUFACTURE OF READY-TO-USE CAKES OF SOAP AND LIKE CLEANSING MATERIALS Filed March 16, 1959 2 Sheets-Sheet 1 IN VEN TOR. Haul. SCI/Ml 77' BY MKW P 15, 1964 P. SCHMiTT 3,149,188

* MANUFACTURE OF READY-TO-USE CAKES 0F SOAP AND LIKE CLEANSING MATERIALS Filed March 16, 1959 2 Sheets-Sheet 2 Tifi.5.

1N VEN TOR. PAUL Soy/-11 r7- mum United States Patent 3,149,138 MANUFACTURE 0F READY-TQ-USE QAKES GE 58A? LIKE CLEANSIENG MATERlAlZS Paul Schrniit, 373 Webster Ava, Jersey Qity, NJ. Filed Mar. 16, E59, r. l lo. 799,643

priority, application Germany, Nov. 7,

less, Sch 24,9ss 2 Claims. (Cl. 264-267) The present invention relates to a method of producing ready-to-use pieces of skin cleansing materials, such as soaps and detergents, and is more particularly applicable to the production of cakes of transparent soap.

The production of ready-to-use cakes of soal has caused many difficulties and, in the case of transparent soap, they have been so great that this novelty-type soap has almost disappeared from the market despite its considerable sales appeal. The production dihiculties are inherent in the properties of transparent soap.

As is known, the transparency of transparent soaps is achieved by a special selection and/or combination of fats, oils or fatty acids as soap components. Furthermore, such soaps contain compounds having one or more alcohol groups, for instance, glycerol, carbohydrates, solvents, etc. This composition of transparent soaps has necessitated the following manufacturing procedure:

The liquid soap base was poured into large molds wherein it was permitted to cool into a rigid soap block. After removal from the molds, the soap blocks were aged for two to three months by storing them dark and cool cellars to harden the soap. This hardening process was necessary because the soap could not be formulated hard enough without interfering with the clean cutting of the blocks into bars, which is done with thin steel wires. During the aging of the relatively soft soap blocks, volatile soap components, such as aromatic substances and alcohols, were lost. Furthermore, the soap blocks dried unevenly since their surface portions dried more rapidly than the interior portions. This unevenness in the drying of the blocks caused the outer soap portions to lose more of the volatile components than the inner portions and also led to clouding of the transparent soap.

The aged soap blocks were cut into bars, the bars were aged some more and the aged bars were cut into pieces which served as blanks for the final pressing operation in which the finished cakes of transparent soap were formed. Before pressing, the blanks had to kept in special conditioning rooms at temperatures of about 37 C. to 4 C. and a relative humidity of about to make them suitable for pressing. Mold burrs then had to be removed from the pressed pieces and their surfaces were polished with soft cloths moistened with a glycerol solution to obtain the ready-to-use cakes of transparent soap.

It is obvious from the above description that the conventional manufacturing method of making transparent soap hers is very cumbersome, tirne-consuming, and expensiv in addition to which it has the following disadvwtages:

During the long storage periods encountered in the manufacture of the soap pieces, the soap is subjected to considerable shrinkage. Even after finishing, the ready-to-use soap ten s toward further shrinkage unless it is packed in special, moisture-impermeable envelopes or containers. This shrinkage entails further losses of aromatic and other volatile soap components. It also causes the smooth surface of the cakes of soap to become deformed and thus diminishes the eye appeal of the article. It may be noted, in this respect, that surface smoothen'ng and polishing is generally a difficult matter in the production of toilet soap. However, while regular, non-transparent soaps usually maintain their smooth surfaces even during extended storage periods, the particular tendency to shrink is a peculiar characteristic of transparent soaps.

Other difliculties encountered with transparent soaps are due to the influence of the surrounding air. High humidity or moisture causes sweating and softening of the outer layer of the transparent soap cake to a smeary unattractive mass. Oxygen oxidizes its ethereal oils. Carbon dioxide combined with oxygen produces a rancid aroma in the soap.

Finally, despite the long aging periods during the manufacturing process, commercially available transparent soaps are relatively soft and are, therefore, rapidly used up.

Due to the process of pressing the soap blanks into final shape, it has not been possible to make any but substantially rectangular transparent soap pieces with slightly rounded edges in an economical manner, thereby avoiding excessive waste in base soap and hand labor during the process of cu g, shaping, or preforming the blank as closely as possible to the final desired shape. No economical and commercially feasible process was available for making transparent soap pieces in the most popular shapes, such as round, oval or hand-conforming cakes.

It is a principal object of the present invention to overcome the above described disadvantages in tse manufacture of read-to-use cakes of transparent skin cleansing materials, such as transparent soap.

It is a concomitant object of the invention to manufacure cakes of transparent soap which retain their desirable properties over extended periods of storage.

It is a further object of the present invention to provide a suitable casting mold container for transparent soap.

The above and other objects in accordance with the present invention are accomplished by casting a liquid mass of a castable soap or detergent into a mold which is designed to serve as a package or container for the ready-to-use cake and subjecting the liquid mass in the mold to cooling whereby the mass solidifies into a cake having the contour of the mold.

In accordance with one preferred feature of the present invention, the molds are air-tightly sealed after casting, whereby the solidified cake in the mold is protected from the atmosphere during storage. In this manner, shrinkage is prevented, the surface of the cake remains smooth and no loss of aromatic or other volatile components takes place. The deleterious effect of oxygen, carbon dioxide, and moisture is entirely removed.

According to another preferred feature of the present invention, the casting mold consists of a suitable plastic having smooth interior or mold surfaces or produce a desirable surface smoothness of the cast soap. Plastic molds with smooth surfaces may be cheaply mass-produced and may have the added advantage of including flexible wall portions whose depression will facilitate the removal of the ready-to-use cake from the mold. If required, the inner mold surface is provided with a very light coating of a suitable mold release agent, such as a silicone resin or a high melting wax of a melting point of 50-60 C. to facilitate separation of the soap cake from the inner mold walls.

The above and other objects, features and advantages of the present invention will be more fully exemplified in the following detailed description of certain embodiments thereof, taken in conjunction with the accompanying drawing, Wherein FIG. 1 schematically illustrates the manufacture of cakes of soap and detergents according to the invention;

FIG. 2 is a section along line 11-11 of FIG. 4 of one embodiment of a casting mold useful in the method of the invention;

PEG. 3 is an end view of the mold of FIG. 2;

FIG. 4 is a top view of the mold of FIGS. 2 and 3;

FIG. 5 is a side view, partly in section, of another embodiment of a casting mold with a preferred sealing means;

FIG. 6 is a side view of yet another embodiment of a casting mold with depressable, arcuate wall portions;

FIG. 7 is a perspective view, partly in section, of a casting mold having a transparent'wall portion.

Referring now to the drawing, FIG. 1 shows a storage tank 1 for a molten mass of castable soap or detergent. A duct 2 connects the .filling funnel or hopper with the storage tank, the flow of the liquid mass being controlled by valve 3. i

Molds 6 (more fully illustrated in FIGS. 2 to 4) are held on conveyor band 5 which moves each mold into alignment with the nozzle of hopper 4, in the direction of arrow 9, so that the liquid mass may be cast into the mold through an inlet opening 13. After the mold has been completely filled with the liquid mass, it is moved on to apparatus '7, which may be any suitable device for sealing the inlet opening. After sealing, the mold is moved further into cooling chamber 3 where the molten mass in the mold is solidified.

In actual practice, a temperature of between about 65 C. and 70 C. for the molten mass during casting has been found to be suitable. While cooling for purposes of solidification of the cast mass in the molds could be effected at room temperature, the present invention provides a special cooling chamber to accelerate the process, the temperature of the cast mass being reduced in the cooling chamber to about 40 C. in a period of about 10 minutes.

One form of a useful mold for the practice of the invention is illustrated in FIGS. 2 to 4. As shown, the twopart mold consists of a lower mold portion 11 and an upper mold portion 10 whose respective rims 11a and 10a overlap when the upper mold portion is united with the lower mold portion. The mold portion rims are perforated at one side to form a relatively small inlet opening 13 permitting the liquid mass to be cast into the mold. An inlet opening of about one fifth of the thickness of the mold, i.e., for instance, of about three to seven millimeters in diameter, has been found satisfactory for the casting method according to the present invention.

The illustrated mold also has two like legs 14 symmetrically arranged at each side of the inlet opening, which enable the mold to he stood up on its side when it is used by the consumer as a container for the cake of soap. Preferably each mold portion 10 and 11 is also provided with two projections 14a opposite to the legs 14. Said legs 14 and the projections 14a extend, as indicated in FIGS. 2 to 4 from the rim portions 10a and 11a towards the center of each mold portionlt) and 11.. They reenforce the rims of the mold portions at the places where they are attached to the mold and, thus, facilitate separation of the mold portions from each other when opening the mold to use the soap cake.

As shown, the mold is circular and has arcuate molding surfaces merging on top and bottom into recessed, flat surface portions 12 and 15 in the center of the mold portions 10 and 11. As will be explained more fully in connection with FIG. 7, the center portions 12 and 15 may be transparent while the remainder of the mold is opaque. Also, these flat portions may serve as pressure points which may be depressed to facilitate removal of the soap from the mold during use.

Any moisture-impermeable material of natural or synthetic origin may be used for the mold, plastics which may be molded or shaped into semi-rigid or rigid bodies being preferred. Such plastic molds may be transparent, translucent, opaque, white, or colored. Useful plastics include polyethylene, polyvinyl chloride and its copolymers, cellulose acetates, cellulose nitrates, ethyl and propyl cellulose, polystyrene, methacrylate polymers, polyamides, phenol formaldehyde resins, amino resins, melamine resins, natural and synthetic rubbers, and like materials.

Polyethylene and polyvinyl chloride resins have been found to be most suitable. I

It is obvious that the shape of the mold will depend only on the desired shape of the cake of soap to be cast therein. Thus, instead of being circular, the mold may be oval, rectangular or of any other desired configuration. The thickness of the mold may vary between 0.5 mm. and 0.7 mm. for instance. Preferably the thickness of the mold portions gradually decreases from its rim towards its center so that it can be depressed more readily by applying pressure to the center parts of the mold portions.

The inlet opening 13 may be sealed after casting merely by placing a stopper thereinto. If the mold and the stopper are, for instance, of synthetic resin, the stopper may be fixed to the mold by autogeneousbonding or by means of a suitable adhesive, as is well known in the art of bonding together plastic bodies.

Instead of a stopper, a simple platelet may be placed over the opening and fixed thereover to effect the desired sealing.

One form of sealing is illustrated in FIG. 5 As shown therein, the mold portions 21 and 22 are generally similar to the mold embodiment of FIGS. 2 to 4. The seam 23 formed at the abutment of the overlapping mold portion rims is sealed in this case with an adhesive band 2 which may be readily torn off to make it possible to lift upper mold portion 21 off lower mold portion 22, to remove the soap cake from the mold, when the consumer is desirous of using the soap, and to put it back into the mold for storage. The advantage of this embodiment lies in the fact that the adhesive band 24 provides a very simple and economical means for air-tightly sealing the mold after casting and eliminates, therefore, the necessity for the rims of the mold portions to fit too tightly, thus facilitating their separation when the mold serves as a soap container during use of the soap.

FIG. 6 shows a modified mold constituted by upper mold portion 25 fitted onto lower mold portion 25, similarly as in the previously described molds. The mold pore tions have central dome portions 27 and 28 which, upon depression, will facilitate the removal of the soap from a mold portion. This may be of particular advantage at the first use of the soap. After the two-part mold container is opened by the consumer, he may find the cast soap to stick somewhat to the upper or the lower mold portion. In this case, light pressure on dome 27 or 28 will readily separate the soap from the mold wall to which it adheres.

FIG. 7 illustrates another two-part mold consisting of upper mold portion 29 and lower mold portion 30 holding a cake of transparent soap 31. In this case, the mold is opaque, except for a central transparent window 43 which makes it possible to read the legend 33 on label 32 embedded in the soap. The legend may consist of a trademark or any other designation.

Alternatively, the legend 33 may be molded into the mold portion itself, thereby forming a corresponding legend to be cast into the soap and eliminating the necessity of placing a desired description or ornamentation on the surface of the soap after its formation, as has been done heretofore.

The considerable advantages of the present method and molds will partly be obvious from the above description and will be more fully elucidated hereinafter. From a point of view of economy, the present invention eliminates the long aging periods of transparent soap in blocks, the cutting of the blocks into bars, the further aging of the bars, the cutting of the bars into blanks, the aging of the blanks and the pressing of the softened blanks into the final cake form. It also obviates removal of mold burrs and polishing of the surface of the finished cakes if the inside molding surfaces of the casting molds are smooth.

Being sealed in its casting mold, the transparentsoap produced in accordance with the present invention does not shrink, retains its aromatic and other volatile components, and has a smooth surface. Since air, i.e. oxygen and carbon dioxide, are excluded from the sealed mold container of this invention, the soap may be stored in the mold containers indefinitely and regardless of the storage conditions, such as temperature, moisture, etc.

The soap may be cast into any desired form, including oval, round and hand-conforming shapes and complex configurations of combined fiat and arcuate surfaces.

The manufacturing costs are lower than with conventional methods and the casting mold, which serves as packing and container for the cast soap, is no more expensive than would be any conventional packing or con tainer.

Most importantly, since no cutting of the soap is involved, a transparent soap produced according to the invention may be cast from a composition giving a harder soap than could be obtained heretofore. Such a harder soap will be much more economical in use than a soft soap while giving a good and fast lather.

As is known, the hardness of the soap may be controlled by a suitable selection of the fatty and oily components in the soap. Thus, soaps richer in higher melting fatty acids, like myristic acid, palmitic acid, or stearic acid, will be harder than soaps containing a larger percentage of lower melting fatty acids, such as oleic acid, ricinoleic acid or linoleic acid. The desired degree of hardness may be obtained by varying the proportions between the fatty acid components. Generally, the median melting point of the fatty components is selected to lie between about C. and 45 C., preferably about C.

The casting method of the present invention not only makes it practically possible to produce a transparent soap of increased hardness but makes this desirable since a relatively soft soap could not be cleanly released from the mold container without impairing its smooth surface.

It is, of course, understood that the transparent soap base may have admixed thereto suitable detergents, anionic or non-ionic surface active agents, Wetting agents, lathering agents, deodorants, emulsifiers, and the like provided these additives do not substantially impair the transparency and castability of the transparent soap bars.

Merely for purposes of illustration and without in any way limiting the invention thereto, the following examples give some formulations found useful for casting in accordance with this invention:

Example 1 100 lbs. of transparent soap were prepared according to the following formulas, I indicating a soft soap which, although suitable for the purpose of the present invention, is less desirable due to is softness, 11 indicating a suitable medium hard transparent soap, and III indicating a suitable hard transparent soap:

was effected in the usual manner and the molten soap was cast into molds, such as illustrated in the accompanying drawing. Clearly transparent medium hard and hard soap cakes were obtained.

6 Example 2 A castable transparent cleansing material was made with natural fats and oils in combination with a synthetic, anionic surface active compound, according to the following formula:

Pounds Sodium lauryl sulfate 8 Tallow 20 Coconut oil 20 Caustic soda (38 Be'.) 20 Glycerol (28 B.) 13 Alcohol 14 Water 5 The above cleansing material was cast according to the invention. The same results were obtained if the sodium lauryl sulfate was substituted by any anionic higher fatty alcohol sulfate, alkyl aryl sulfonate, alkyl arylamine sulfonate, sodium alkyl sulfonate, or sulfated and sulfonated amides.

Example 3 A similar castable transparent cleansing material as in Example 2 was prepared by replacing the anionic compounds by non-ionic surface-active compounds, such as polyhydric alcohol higher fatty acid esters, amide condensates such as the alkylamides of lanolic acids, or polyethylene oxide alkyl phenols, the following formulation being typical:

Of course, many changes and variations in the composition of the soap and detergent, in the shape and composition of the mold, in the manner of filling, sealing, and cooling the molds, and the like may be made by those skilled in the art in accordance with the principles set forth herein and in the claims annexed hereto.

I claim:

1. A method of manufacturing a ready-to-use cake of transparent soap, comprising the steps of casting a liquid mass of said soap into the aperture of a transparent plastic mold having interior molding surfaces conforming to the desired shape of the cake so as to completely fill the mold, said mold being at least partly flexible, sealing the mold aperture following casting and before solidification of the soap, permitting the liquid mass to cool in the mold to solidify therein in said desired shape, and maintaining the solidified cake of transparent soap in the sealed-mold until it is ready to be used.

2. The method of claim 1, wherein the mold is airtightly sealed after casting.

References Cited in the file of this patent UNITED STATES PATENTS 1,244,297 Curland Oct. 23, 1917 1,268,126 Jones June 4, 1918 1,353,978 Jergens Apr. 12, 1932 2,335,766 Kinloch Nov. 30, 1943 2,508,578 Marshall May 23, 1950 2,932,386 Ushkow Apr. 12, 1960

Claims (1)

1. A METHOD OF MANUFACTURING A READY-TO-USE CAKE OF TRANSPARENT SOAP, COMPRISING THE STEPS OF CASTING A LIQUID MASS OF SAID SOAP INTO THE APERTURE OF A TRANSPARENT PLASTIC MOLD HAVING INTERIOR MOLDING SURFACES CONFORMING TO THE DESIRED SHAPE OF THE CAKE SO AS TO COMPLETELY FILL THE MOLD, SAID MOLD BEING AT LEAST PARTLY FLEXIBLE, SEALING THE MOLD APERTURE FOLLOWING CASTING AND BEFORE SOLIDIFICATION OF THE SOAP, PERMITTING THE LIQUID MASS TO

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